Genesis OPC Explorer 3.0
Genesis OPC Server View: Addition, Modification and Removal of Calculated OPC Item(s)
About Genesis OPC Explorer 3.0
Language: Visual C++
Size: 12.009 Kb
Installation File: 6826 Kb
The copyrights for Genesis OPC Explorer 3.0 belong to TGMDev. You are allowed to copy and distribute this software provided that it remains unaltered (No software Addition) and free (except a small fee for the software distribution)
Genesis OPC Explorer 3.0 is a freeware but you can contribute to its development by supporting TGMDev.
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Addition, Modification and Removal of Calculated OPC Item(s)
Adding acquired Item(s) to an OPC Group requires beforehand
1. Addition of Calculated OPC Item(s)
Trigger Calculated OPC Item(s) Addition
Two methods are available to start the addition of Calculated OPC Item(s)
The 'OPC Item Addition, Modification and Removal' dialog box pops up.
Note that the available acquired OPC items list on the left of the dialog box with Qualified Name and Short Name. The Short Names will be used to make calculation easier.
Suppose you want to compute the normalized flow from the acquired data: Flow (FY_201), Temperature (TY_001) and Pressure (PY_201).
using the formula: Flow Normalized = Measured Flow × (Temperature K Normal / Measured Temperature K) × ( Abs Measured Pressure / Abs Normal Pressure)
where Temperature K is the temperature in Kelvin ( that is Temperature C° + 273.16). Normal Pressure will be 1.033 Bar.
Here are the procedure to add this computation:
Click on the 'Add Item' button to Add the Item to the Calculated Item List. The Dialog Box willl then show the new configuration of the OPC group:
Additional features are available to get calculated values:
Select one built-in function by cliccking the pull-down button of the Combobox 'Available Functions'
The function will be inserted at the caret position. Move the caret inside the function parenthesis and add an acquired OPC data using the 'Insert Acquired Item in Expression' button. Note that you can also insert calculated data (see next point)
Calculated data can be used in other calculated data expression provided that ....it is computed before !!!
Taking the exemple of computing the normalized flow from the acquired data, this can be done in simpler steps:
Compute Kelvin Temperature: TY_001_K = TY_001 + 273.16
Absolute Pressure PY_201_ABS = PY_201 + 1.033
Normmalized Flow = FY_201 * ( 273.16 / TY_001_K) * ( PY_201_ABS / 1.033)
Obviously, Indirect calculated items are valid only if intermediary calculated items are already calculated and valid.
Date of Last Modification: 25-09-2018
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